Acta Cryst. (2008). E64, o939 [ doi:10.1107/S160053680801146X ]
The title compound, C10H14O5, is an intermediate in our study of the asymmetric synthesis of ![[alpha]](/logos/entities/alpha_rmgif.gif)
-hydroxyalkanoic acids. The structure consists of 1,4-dioxaspiro[4,5]decane skeleton formed when the cyclohexylidene group binds to both of the hydroxyl groups of carboxylic groups of the starting malic acid. The six-membered ring adopts a chair conformation.
Freshly distilled cyclohexanone (5.60 ml, 56.00 mmol) and BF3˙OEt2 (9.40 ml, 73.30 mmol) was added to a suspension solution of L-(-)-malic acid (5.01 g, 37.39 mmol) in dry ether (62.0 ml) cooled at 0 oC. The suspension gradually turned into a clear solution. After the mixture was stirred for 1 h at 0 oC, the ice bath was then removed and the mixture was stirred for 12 h at room temperature. The reaction mixture was diluted with ether and washed with 10% aqueous NaOAc (4 x 20.0 ml). The combined aqueous layers were extracted with ether, and the combined organic phases were washed three times with brine and dried over MgSO4. Removal of solvent in vacuo afforded a crude acid as pale yellow oil. Recrystallization (ethyl acetate /n-hexane) afforded 4.426 g (83%) of the acid 2 as an off-white crystal: Rf = 0.40 (ethyl acetate – n-hexane, 1/1, v/v); [a] 21D = + 6.6° (c 1.2, CHCl3); 1H NMR (300 MHz, CDCl3) δ 9.29 (bs, 1H), 4.72 (dd, 1H, J = 6.3, 3.9 Hz), 2.99 and 2.86 (ABX, 2H, JAB = 17.3, JAX = 6.3, JBX = 3.9 Hz), 1.89–1.30 (m, 10H).
The C-bound H atoms were placed in calculated positions (C-H = 0.97 - 0.98 Å) and included in the refinement in the riding-model approximation, with Uiso(H) = 1.2or 1.5Ueq(C). The hydroxy H atoms were constrained to ideal geometries with O-H = 0.82 Å and Uiso(H) = 1.5Ueq(O).
Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
![[Figure 1]](./wk2081fig1thm.gif)
| Fig. 1. The molecular structure of the title compound, showing the atom numbering scheme. Displacement ellipsoids for non-H atoms are represented at the 30% probability level. The H atoms are drawn with an arbitrary radius. |
| C10H14O5 | F000 = 456 |
| Mr = 214.21 | Dx = 1.338 Mg m−3 |
| Orthorhombic, P212121 | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: P 2ac 2ab | Cell parameters from 3702 reflections |
| a = 6.7098 (6) Å | θ = 2.4–31.6º |
| b = 10.3463 (8) Å | µ = 0.11 mm−1 |
| c = 15.3175 (13) Å | T = 295 (2) K |
| V = 1063.37 (15) Å3 | Tabular, colourless |
| Z = 4 | 0.50 × 0.45 × 0.35 mm |
| Bruker Kappa APEXII CCD diffractometer | 2206 independent reflections |
| Radiation source: fine-focus sealed tube | 1814 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.022 |
| T = 295(2) K | θmax = 33.3º |
| ω scans | θmin = 2.4º |
| Absorption correction: multi-scan (SADABS; Bruker, 2004 | h = −10→8 |
| Tmin = 0.948, Tmax = 0.963 | k = −15→9 |
| 7861 measured reflections | l = −13→22 |
| Refinement on F2 | Hydrogen site location: difference Fourier map |
| Least-squares matrix: full | H-atom parameters constrained |
| R[F2 > 2σ(F2)] = 0.041 | w = 1/[σ2(Fo2) + (0.0907P)2 + 0.0732P] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.123 | (Δ/σ)max < 0.001 |
| S = 1.05 | Δρmax = 0.31 e Å−3 |
| 2206 reflections | Δρmin = −0.17 e Å−3 |
| 138 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
| Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.077 (9) |
| Secondary atom site location: difference Fourier map |
| C10H14O5 | V = 1063.37 (15) Å3 |
| Mr = 214.21 | Z = 4 |
| Orthorhombic, P212121 | Mo Kα |
| a = 6.7098 (6) Å | µ = 0.11 mm−1 |
| b = 10.3463 (8) Å | T = 295 (2) K |
| c = 15.3175 (13) Å | 0.50 × 0.45 × 0.35 mm |
| Bruker Kappa APEXII CCD diffractometer | 2206 independent reflections |
| Absorption correction: multi-scan (SADABS; Bruker, 2004 | 1814 reflections with I > 2σ(I) |
| Tmin = 0.948, Tmax = 0.963 | Rint = 0.022 |
| 7861 measured reflections |
| R[F2 > 2σ(F2)] = 0.041 | Δρmax = 0.31 e Å−3 |
| wR(F2) = 0.123 | Δρmin = −0.17 e Å−3 |
| S = 1.05 | Absolute structure: ? |
| 2206 reflections | Flack parameter: ? |
| 138 parameters | Rogers parameter: ? |
| H-atom parameters constrained |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
| x | y | z | Uiso*/Ueq | ||
| O1 | 0.7046 (2) | 0.66387 (12) | 0.06930 (8) | 0.0516 (3) | |
| O2 | 0.4717 (2) | 0.51238 (14) | 0.10628 (8) | 0.0584 (4) | |
| O3 | 0.2465 (2) | 0.28916 (12) | 0.00641 (11) | 0.0613 (4) | |
| O4 | −0.0034 (2) | 0.40271 (14) | −0.04693 (12) | 0.0647 (4) | |
| H4A | −0.0620 | 0.3336 | −0.0414 | 0.097* | |
| O5 | 0.6684 (3) | 0.66532 (14) | −0.07558 (9) | 0.0614 (4) | |
| C1 | 0.6310 (2) | 0.61950 (15) | −0.00602 (11) | 0.0438 (3) | |
| C2 | 0.4985 (3) | 0.50524 (14) | 0.01414 (10) | 0.0406 (3) | |
| H2A | 0.5662 | 0.4245 | −0.0015 | 0.049* | |
| C3 | 0.2983 (3) | 0.51228 (15) | −0.03022 (12) | 0.0454 (3) | |
| H3A | 0.2220 | 0.5827 | −0.0051 | 0.055* | |
| H3B | 0.3176 | 0.5309 | −0.0917 | 0.055* | |
| C4 | 0.1827 (2) | 0.38946 (15) | −0.02119 (10) | 0.0393 (3) | |
| C5 | 0.6327 (3) | 0.58484 (16) | 0.14185 (11) | 0.0461 (4) | |
| C6 | 0.5544 (4) | 0.6724 (2) | 0.21270 (13) | 0.0615 (5) | |
| H6A | 0.4875 | 0.6209 | 0.2568 | 0.074* | |
| H6B | 0.4577 | 0.7317 | 0.1880 | 0.074* | |
| C7 | 0.7215 (5) | 0.7482 (2) | 0.25453 (14) | 0.0702 (7) | |
| H7A | 0.7760 | 0.8083 | 0.2122 | 0.084* | |
| H7B | 0.6687 | 0.7981 | 0.3029 | 0.084* | |
| C8 | 0.8859 (4) | 0.6613 (2) | 0.28737 (14) | 0.0686 (6) | |
| H8A | 0.8347 | 0.6064 | 0.3336 | 0.082* | |
| H8B | 0.9925 | 0.7136 | 0.3114 | 0.082* | |
| C9 | 0.9671 (3) | 0.5778 (2) | 0.21429 (14) | 0.0643 (5) | |
| H9A | 1.0289 | 0.6322 | 0.1704 | 0.077* | |
| H9B | 1.0681 | 0.5200 | 0.2372 | 0.077* | |
| C10 | 0.8011 (3) | 0.49950 (18) | 0.17303 (13) | 0.0547 (4) | |
| H10A | 0.8540 | 0.4511 | 0.1240 | 0.066* | |
| H10B | 0.7502 | 0.4381 | 0.2154 | 0.066* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| O1 | 0.0599 (8) | 0.0417 (6) | 0.0531 (6) | −0.0192 (6) | −0.0063 (6) | 0.0093 (5) |
| O2 | 0.0631 (8) | 0.0668 (8) | 0.0454 (6) | −0.0280 (7) | −0.0004 (6) | 0.0098 (6) |
| O3 | 0.0445 (6) | 0.0356 (5) | 0.1039 (11) | −0.0022 (5) | −0.0091 (7) | 0.0121 (7) |
| O4 | 0.0425 (6) | 0.0513 (7) | 0.1003 (11) | −0.0049 (6) | −0.0158 (7) | 0.0192 (7) |
| O5 | 0.0622 (8) | 0.0654 (9) | 0.0565 (7) | −0.0148 (7) | 0.0016 (6) | 0.0219 (7) |
| C1 | 0.0436 (7) | 0.0370 (6) | 0.0509 (8) | −0.0079 (6) | 0.0021 (7) | 0.0086 (6) |
| C2 | 0.0434 (7) | 0.0330 (6) | 0.0455 (7) | −0.0058 (6) | −0.0007 (6) | 0.0048 (6) |
| C3 | 0.0436 (7) | 0.0360 (7) | 0.0568 (8) | −0.0043 (6) | −0.0036 (7) | 0.0096 (6) |
| C4 | 0.0376 (6) | 0.0365 (6) | 0.0440 (7) | −0.0006 (6) | −0.0002 (6) | 0.0009 (5) |
| C5 | 0.0516 (9) | 0.0420 (7) | 0.0448 (7) | −0.0098 (7) | −0.0003 (7) | 0.0040 (6) |
| C6 | 0.0602 (11) | 0.0677 (12) | 0.0564 (10) | 0.0122 (10) | −0.0036 (9) | −0.0061 (9) |
| C7 | 0.0984 (19) | 0.0535 (11) | 0.0588 (11) | 0.0035 (11) | −0.0118 (12) | −0.0117 (9) |
| C8 | 0.0772 (15) | 0.0712 (13) | 0.0575 (10) | −0.0108 (12) | −0.0193 (10) | −0.0002 (10) |
| C9 | 0.0513 (10) | 0.0734 (13) | 0.0683 (11) | 0.0032 (10) | −0.0065 (9) | 0.0130 (11) |
| C10 | 0.0663 (11) | 0.0425 (8) | 0.0552 (8) | 0.0047 (9) | 0.0025 (9) | 0.0053 (7) |
| O1—C1 | 1.336 (2) | C5—C10 | 1.511 (3) |
| O1—C5 | 1.4617 (19) | C6—C7 | 1.511 (3) |
| O2—C5 | 1.423 (2) | C6—H6A | 0.9700 |
| O2—C2 | 1.425 (2) | C6—H6B | 0.9700 |
| O3—C4 | 1.199 (2) | C7—C8 | 1.510 (4) |
| O4—C4 | 1.317 (2) | C7—H7A | 0.9700 |
| O4—H4A | 0.8200 | C7—H7B | 0.9700 |
| O5—C1 | 1.193 (2) | C8—C9 | 1.515 (3) |
| C1—C2 | 1.511 (2) | C8—H8A | 0.9700 |
| C2—C3 | 1.507 (2) | C8—H8B | 0.9700 |
| C2—H2A | 0.9800 | C9—C10 | 1.515 (3) |
| C3—C4 | 1.495 (2) | C9—H9A | 0.9700 |
| C3—H3A | 0.9700 | C9—H9B | 0.9700 |
| C3—H3B | 0.9700 | C10—H10A | 0.9700 |
| C5—C6 | 1.508 (3) | C10—H10B | 0.9700 |
| C1—O1—C5 | 110.00 (12) | C7—C6—H6A | 109.4 |
| C5—O2—C2 | 108.11 (13) | C5—C6—H6B | 109.4 |
| C4—O4—H4A | 109.5 | C7—C6—H6B | 109.4 |
| O5—C1—O1 | 123.82 (15) | H6A—C6—H6B | 108.0 |
| O5—C1—C2 | 128.12 (16) | C8—C7—C6 | 111.94 (17) |
| O1—C1—C2 | 108.05 (13) | C8—C7—H7A | 109.2 |
| O2—C2—C3 | 109.37 (15) | C6—C7—H7A | 109.2 |
| O2—C2—C1 | 103.66 (13) | C8—C7—H7B | 109.2 |
| C3—C2—C1 | 113.23 (12) | C6—C7—H7B | 109.2 |
| O2—C2—H2A | 110.1 | H7A—C7—H7B | 107.9 |
| C3—C2—H2A | 110.1 | C7—C8—C9 | 110.88 (17) |
| C1—C2—H2A | 110.1 | C7—C8—H8A | 109.5 |
| C4—C3—C2 | 112.30 (13) | C9—C8—H8A | 109.5 |
| C4—C3—H3A | 109.1 | C7—C8—H8B | 109.5 |
| C2—C3—H3A | 109.1 | C9—C8—H8B | 109.5 |
| C4—C3—H3B | 109.1 | H8A—C8—H8B | 108.1 |
| C2—C3—H3B | 109.1 | C10—C9—C8 | 110.37 (19) |
| H3A—C3—H3B | 107.9 | C10—C9—H9A | 109.6 |
| O3—C4—O4 | 122.26 (15) | C8—C9—H9A | 109.6 |
| O3—C4—C3 | 125.67 (15) | C10—C9—H9B | 109.6 |
| O4—C4—C3 | 112.07 (14) | C8—C9—H9B | 109.6 |
| O2—C5—O1 | 104.72 (12) | H9A—C9—H9B | 108.1 |
| O2—C5—C6 | 109.10 (17) | C5—C10—C9 | 111.66 (15) |
| O1—C5—C6 | 109.04 (14) | C5—C10—H10A | 109.3 |
| O2—C5—C10 | 112.38 (15) | C9—C10—H10A | 109.3 |
| O1—C5—C10 | 108.68 (15) | C5—C10—H10B | 109.3 |
| C6—C5—C10 | 112.58 (15) | C9—C10—H10B | 109.3 |
| C5—C6—C7 | 111.0 (2) | H10A—C10—H10B | 107.9 |
| C5—C6—H6A | 109.4 |
We gratefully acknowledge financial support in part from the National Science Council, Taiwan (NSC 96-2113-M-033-003) and in part from the project of the specific research fields in the Chung Yuan Christian University, Taiwan, under grant CYCU-95-CR-CH.
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Enantiomerically pure α-hydroxy carboxylic acids are an important class of biological molecules (Liang et al., 2000; Sitachitta et al., 2000; Horgen et al., 2000) as well as important intermediates for the synthesis of natural products (Coppola & Schuster, 1997; Sugiyama et al., 1990; Heimgartner & Obrecht, 1990). For the above reasons, asymmetric synthesis of α-hydroxy carboxylic acids has attracted considerable attention. A number of synthetic strategies for preparing the optically active α-hydroxy carboxylic acids have been published in the literature (Dixon et al., 2005; Díez et al., 2001; Coppola & Schuster, 1997). The synthesis of the optically pure title compound ([a] 20 D = + 6.6°) (Scheme 1), which is an intermediate of our study on the asymmetric synthesis of α-hydroxyalkanoic acids, was carried out according to the reported method (Hanessian et al., 1993) starting with the commercial optical pure L-(-)-malic acid. Herein, we report the single-crystal structure (Fig. 1) of the title compound. The crude product was recrystalized from ethyl acetate – n-hexane at room temperature, which allowed us to observe the single-crystal of the title compound. Notably, the cyclohexylidene group was bonded at the hydroxyl groups of carboxylic group (C-1) and on C-2 to show the spirocyclic structure.